Recent content by WW Kayaker

Sorry, for some reason my email stopped sending notifications of replies to this thread so I just now saw the most recent comments. Thanks for all the helpful information. I'll try to address all the recent points below. If any question is unanswered let me know and I'll do so. Baluncore...

That sounds very interesting about phase velocity. I'm not familiar with the concept and didn't quite get it, but it definitely makes sense that a perfectly flat slap is going to be a harder landing (I've experienced it too from 20 ft in not very aerated water). About the adjusting the springs...

JBA, thanks. I realize they return the energy but wouldn't the purpose of reducing the force of impact still be accomplished? The energy would be returned after the impact is over so it wouldn't add to the impact, correct? I had considered dampers but I would need one that is conventional, i.e...

Baluncore, the spring is not intended to absorb the entire impact of the fall but only to add to the absorption capability which the water already had as noted in the OP. Indeed, if the whole impact of a 20 ft fall was absorbed in two inches that would be 120 G (neglecting any energy absorbed by...

Thanks, Baluncore. Space under the seat is indeed limited. However, I've come up with a couple different lever sort of arrangements that allow the springs to be somewhere other than under the seat and also direct the force of the springs to opposite ends of an aluminum frame, thus keeping it...

EDIT: I'm not sure the calcs below are correct because of units used. Is the following formula from your spreadsheet correct? "Es = Energy Absorbed by Spring (lb-ft) = 1/2 x k x dD^2 =_________" It seems like since the spring rate (k) is in lb/in and the distance the spring travels is also in...

Here's another impact from 22 ft in slow motion. The boat didn't go much into the water so it was a hard hit. Start at 26 seconds into the video:

If the kayak enters the water at an angle it will go deeper but if the landing is flat it does stay on the surface. I can't quite picture what you're referring to with the raft but would assume it entered with angle? I've had one flat landing from about twenty feet into very aerated water and it...

Here's a short clip of an almost perfectly flat landing off of a twenty foot waterfall. I hit pretty hard on this one but tucked forward so it was ok. I don't have the view from the outside handy at the moment but you can sort of see the impact from the helmet cam.

scottdave, Good questions. The 6 inches figure is the number I have seen given by Pat Keller, the most prominent figure when it comes to kayaking waterfalls. Obviously, the amount of aeration in the water makes a huge difference but in my experience the depth of impact off of 20 ft drops has...

Working on installing shocks in my kayak seat to protect my back when landing flat off of tall waterfalls (necessary when there isn't a deep pool). I can't figure out if it will actually help. I guess you would call this a spring and damper in series problem (the damper being the water). Here's...